LOWRI Morgan likes to run to the top of Snowdon and back again. And then do it all over again, within seven hours. Or race a double marathon and then jog a further 60 home, all as a way of keeping herself in peak condition. But this week S4C’s fittest presenter is pushing herself to extremes, when she sets out to tackle the world’s toughest race – the 6633 Ultra Marathon, running 350 miles in the Arctic Circle along Canada’s snowy Dempster Highway.

She’ll be one of just 20 taking part, and hopes to complete it in under 190 hours. But only six people have finished the race since the first one in 2007 – a woman holds the current record – and nobody crossed the finish line last year.

She’ll have to carry all her provisions for the race, from the Yukon’s Eagle Plains to the banks of the Arctic Ocean at Tuktoyaktuk, including food, cooking items, clothing, sleeping kit and safety gear.

And it’s all being filmed for S4C’s Ras yn Erbyn Amser – though the three-strong camera crew will be driving alongside in a truck, finding their own shelter, instead of running with her, as in previous shows, such as the Amazon’s Jungle Marathon, where she finished in the top 10.

On Thursday, in the first of four parts, we see her preparing for the race and subsequent shows follow her bid for race success.

So why does she do it?

"After the Jungle Marathon, I felt lost and it was five months before I wore my running shoes again," explained Lowri, as she packed for her trip to Canada.

"I lost my toenails, had blisters on the bottom of my feet and my whole body shut down. I really needed to rest.

"But the challenge in front of me now is bigger than I could ever have imagined and the consequences – if things go wrong – could be life-threatening.

"I love pushing the boundaries beyond what people consider normal."

During her Arctic challenge, Lowri will battle against temperatures of around -30°C to -40°C. In recent years, temperatures have even plummeted to a teeth-chattering -93°C.

In a bid to acclimatise to the conditions, Lowri’s trained intensively over the past 12 months. She runs more than 140 miles a week, and has experienced the freezing temperatures of Sweden, training with elite forces in survival techniques, and is now accustomed to the kit she’ll be using en route.

She added: "The ability to look after yourself in below-freezing temperatures is as much part of the preparation as perfecting your fitness.

"The key to success is a third physical fitness, a third mental approach and a third down to your systems, how you look after yourself, from cooking to personal cleanliness.

"Closing the zip of a sleeping bag sounds a simple task, but add exhaustion to the extreme conditions and it becomes much more difficult.

"The key to success is good preparation, but no matter how well you prepare back home, it’s a different kettle of fish when you face the challenge in the Arctic.

"In the past, people have lost fingers and toes while taking part!

"But despite all the bad things that could happen, I’m really looking forward to getting started. The 6633 Ultra has played a big part in my life over the past year and I long to hear the sound of the whistle on the starting line."

She’s also be looking to the night skies and the aurora borealis, often seen in spring, for inspiration.

"Seeing the Northern Lights will be a psychological boost for me," said Lowri.

"I saw them in Sweden when I was training and it was -60°C. I was very low and cold and then the Lights started – it was a fantastic morale boost."

Lowri will be raising money for Shelter Cymru during the race. Sponsor her at sheltercymru.org.uk